1. Field of the Invention
This invention relates to a process for preparing isobutyric acid.
More specifically, this invention relates to a process for preparing isobutyric acid by oxidation of isobutyraldehyde with a molecular oxygen-containing gas.
2. Description of the Prior Art
Isobutyric acid is useful as a food additive or as a starting material for the production of methacrylic acid and methyl methacrylate.
It is known to oxidize isobutyraldehyde with molecular oxygen in the presence of a catalyst in order to prepare isobutyric acid as described in, for example, J. Org. Chem., 26, 565 (1961); British Pat. No. 824,116 and Japanese Patent Publication No. 39010/77. However, these prior art processes are not satisfactory in terms of selectivity to isobutyric acid, conversion of isobutyraldehyde and selectivity to by-products such as acetone (hereinafter referred to as "AT"), peroxides (hereinafter referred to as "PO"), isopropyl alcohol (hereinafter referred to as "IPA") and the like.
It has now been found that the above-mentioned problems can be solved by a new improved process and this invention has been accomplished.